1. Field of the Invention
The present invention relates to a printing device, a printing method, and a computer-readable storage medium, in which printing data is continuously printed, by use of plural printers (referred to as printer devices), to a printing medium having a continuous sheet or a roll sheet.
More particularly, the present invention relates to a method by which, in the case of continuous control for continuously printing printing data on the front surface and the back surface of the printing medium by use of two printers or for printing the printing data with two colors on a single surface (e.g., the front surface) of the printing medium, correct printing data is printed onto the printing medium by matching a printing surface of the printing medium which is printed by one printer to a printing surface thereof which is printed by the other printer.
2. Description of the Related Art
When a master printer prints one surface (e.g., front surface) of a continuous sheet or a roll sheet and a slave printer prints another surface (e.g., back surface) thereof and the two printers performs the continuous control operation, a mark indicating a page or printing data such as a barcode is generally formed onto one surface of the sheet in the case of printing on the master printer (ordinarily, referred to as page marking) and a reading sensor arranged to the slave printer reads the mark so as to match information on the printing data on the one surface of the sheet with information on the printing data on the other surface thereof (for the purpose of e.g., matching of the front and the back surfaces). When the image data is printed with two colors on the one surface (e.g., front surface) of the sheet by use of the master printer and the slave printer, that the one surface and the other surface become the same surface requires attention.
In other words, in the case of printing the sheet under the continuous control, the mark is read and it is recognized which printing data is printed on the one surface. Thereafter, the slave printer prints the correct printing data on the other surface of the sheet. Consequently, when the deflection of sheet, etc. causes any abnormal state during conveying the sheet to the slave printer from the master printer, the abnormal state is easily detected by the above matching. The printing data can be printed on the surface of the sheet without errors.
Here, it is typically assumed that the printing data is continuously printed on the front surface and the back surface of the sheet with two printers using electrostatic transfer. In this case, a surface of a photosensitive drum in the master printer is charged and then it is selectively exposed by laser beams, thereby forming an electrostatic latent image corresponding to desired image data. Next, the electrostatic latent image is developed by a developer and then it is transferred to the front surface of the sheet, thereby fixing and forming the image data onto the front surface of the sheet. At this stage, the printing data corresponding to the desired image data is printed onto the front surface of the sheet.
The electrostatic latent image and the image data are formed and the mark such as a barcode indicating the sheet page or image data is formed at a predetermined position on the sheet, thereby performing the page marking on the master printer side.
Further, a reading sensor arranged to the slave printer reads the mark and it is recognized which image data is formed onto the front surface of the sheet, thereby matching the image data on the front surface of the sheet to the image data on the back surface (matching of the front and back surfaces). As a result of the matching of the front and back surfaces, when it is confirmed that information on the image data on the back surface of the sheet is correct, the correct image data is formed onto the back surface of the sheet by a process similar to that for forming the image data on the front surface of the sheet on the master printer side as previously described.
Conventionally, the mark such as the barcode formed by the above-mentioned page marking is printed at an edge portion of the sheet such as a continuous sheet or a roll sheet (e.g., position of the perforation) or at a constant position from the head portion of the image data. During printing the printing data corresponding to the image data onto the front surface of the sheet, the sheet is continuously conveyed. In this case, the sheet size (or the size of the image data) is changed and then a positional relationship between the mark such as the barcode and the reading sensor in the slave printer is changed. Therefore, when the sheet conveying operation stops, the mark might stop just at the position of the reading sensor. Generally, the reading sensor has only a function for detecting the passage of the mark at the position of the reading sensor. Thus, when the mark stops at the position of the reading sensor, the sheet conveying operation starts again for the purpose of printing the back surface of the sheet and then the inconvenience is caused that the reading sensor correctly does not read the mark.
In order to prevent the inconvenience, the reading sensor arranged to the slave printer is a movable one and the position of the reading sensor is moved in parallel with the sheet conveying direction so as to prevent the mark position from being at the position of the reading sensor per sheet size or per size of the image data. Thus, the position of the reading sensor can movably be arranged so as not to locate the mark at the position of the reading sensor when the sheet conveying operation stops.
However, in this case, it is necessary to newly provide, in the slave printer, a mechanism part such as a driving unit for moving the position of the reading sensor in the printer. Generally, the structure of the mechanism part for moving the position of the reading sensor is complicated, and there are problems that the apparatus including the printer is increased in size, and the manufacturing costs of the apparatus rise. Here, the description is given of the case of continuously printing the printing data on the front surface and the back surface of the sheet by use of the two printers. Even in the case of printing the printing data with two colors onto one surface of the sheet by use of the two printers, the similar problems are caused.